The art of glass container manufacture is currently dominated by the so-called individual section or IS machine. Such machines comprise a plurality of separate or individual manufacturing sections, each of which includes a multiplicity of operating mechanisms for converting gobs of molten glass into hollow glass containers. In general, each section includes a parison mold in which a glass gob is initially formed in a blowing or pressing operation, an invert arm for transferring the parison to a blow mold in which the container is blown to final form, and tongs for removing the container for transfer to an annealing lehr. Additional mechanisms provide for closure of mold halves, movement of baffles and blowing nozzles, control of mold cooling wind, etc. U.S. Pat. No. 4,362,544 includes a comprehensive background discussion of the art of both blow-and-blow and press-and-blow glassware forming processes, and also discloses an electropneumatic individual section machine adapted for use in either process.
Initially, the operating mechanisms of each machine section were operated by pneumatic valves carried by a valve block and responsive to cams mounted on a timing shaft coupled to the machine. Synchronism among the mechanisms within each section, and among the various sections of the machine, was therefore controlled by the timing shaft and the valve drive cams. U.S. Pat. No. 4,152,134 discloses an improved control arrangement in which a machine supervisory computer (MSC) is connected to a plurality of individual section computers (ISC) each associated with a corresponding section of the IS machine. Each individual section computer is connected through an associated section operator console (SOC) to solenoid valves in an electropneumatic valve block, which are responsive to electronic valve control signals from the section computer and operator console for controlling operation of the associated section operating mechanisms. A timing pulse generator is connected to the machine supervisory computer and to the individual section computers for synchronizing operation within and among the individual sections. The individual section computer and the section operator console illustrated in the noted patent were subsequently combined in a computerized section operator console (COM-SOC, a trademark of applicant's assignee).
Although the glassware manufacturing systems disclosed in the noted patents, as well as the several additional patents referenced hereinafter, have enjoyed substantial commercial acceptance and success, further improvements remain desirable. For example, although it has heretofore been proposed in U.S. Pat. No. 4,394,148 to provide a driver circuit for each solenoid valve that generates a signal in the event of a circuit fault condition, such fault conditions have not heretofore been readily associateable by an operator with specific operating mechanism in the IS machine. Nor has a driver or solenoid fault condition resulted in either an indication of corrective action to be taken by an operator, or automatically initiation of action at the IS machine independent of operator intervention.
U.S. Pat. Nos. 4,338,115 and 4,364,764 discuss, among other principles, controlled termination of IS machine operation in the event of either an emergency stop or a programmed stop situation. In general, an emergency stop situation is one that calls for termination of motion at all operating mechanisms as quickly as possible, while a programmed stop situation is one that calls for termination of motion in a programmed manner that may facilitate subsequent restart of the machine. In prior art control systems, diodes and/or jumper wires are installed to interface the emergency stop and programmed stop switch or relay contacts to the solenoid valve drivers for initiating the stop sequences in the desired manner for a particular machine. These hardware arrangements thus operated to dedicate the controller to a specific IS machine or machine configuration, reducing desirable manufacturing flexibility.
U.S. Pat. Nos. 4,339,260 and 4,362,544 disclose disposition of the COM-SOC unit on a wireway of the IS machine frame, and connection of the unit to the separate solenoid valves in associated valve blocks by multiple-conductor cables. In a machine section having a valve block or blocks with ninety-six solenoid valves (including spares), for example, there would be ninety-six conductors running through the frame wireway for each machine section, or nine hundred sixty conductors for a ten-section machine. These cables increase the cost of the installation.
It is therefore a general object of the present invention to provide a system and method for control of glass production that alleviate some or all of the problems and difficulties hereinabove set forth. Another and more specific object of the present invention is to provide a system and method of the described character in which fault conditions at one or more of the solenoid valves and/or valve drivers provides an automatic indication of the associated mechanism in the IS machine, and initiates corrective or evasive action as is appropriate for that particular machine mechanism. Another object of the present invention is to provide a system and method of the described character in which responsiveness of the controller and valve drivers to externally generated stop situations--i.e., emergency stop and programmed stop situations--is selectively and electronically programmable through the control computer, thereby making the controller readily adaptable for use in conjunction with a variety of IS machines and machine configurations. Another object of the present invention is to provide a system and method of the described character in which the valve drivers are positioned separately from the COM-SOC controller and connected thereto by a bi-directional serial communication line, reducing the cost of such interconnection, increasing flexibility of the control system, and increasing availability of cooling air flow through the machine frame plenum on which the COM-SOC is mounted. Another and related object of the present invention is to provide a system and method in which activation of the valve drivers is synchronized to the machine timing signal, so that all valves are activated/deactivated substantially simultaneously at each system operating step.